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Message-ID: <PH0PR11MB5830CB1F9EC76D45FA3E0C56D8E72@PH0PR11MB5830.namprd11.prod.outlook.com>
Date: Mon, 20 Jan 2025 10:06:25 +0000
From: "Song, Yoong Siang" <yoong.siang.song@...el.com>
To: "Abdul Rahim, Faizal" <faizal.abdul.rahim@...ux.intel.com>, "David S .
Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, "Jakub
Kicinski" <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Simon Horman
<horms@...nel.org>, Willem de Bruijn <willemb@...gle.com>, "Bezdeka, Florian"
<florian.bezdeka@...mens.com>, Donald Hunter <donald.hunter@...il.com>,
Jonathan Corbet <corbet@....net>, Bjorn Topel <bjorn@...nel.org>, "Karlsson,
Magnus" <magnus.karlsson@...el.com>, "Fijalkowski, Maciej"
<maciej.fijalkowski@...el.com>, Jonathan Lemon <jonathan.lemon@...il.com>,
Andrew Lunn <andrew+netdev@...n.ch>, Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>, Jesper Dangaard Brouer
<hawk@...nel.org>, John Fastabend <john.fastabend@...il.com>, "Damato, Joe"
<jdamato@...tly.com>, Stanislav Fomichev <sdf@...ichev.me>, Xuan Zhuo
<xuanzhuo@...ux.alibaba.com>, Mina Almasry <almasrymina@...gle.com>, "Daniel
Jurgens" <danielj@...dia.com>, Andrii Nakryiko <andrii@...nel.org>, "Eduard
Zingerman" <eddyz87@...il.com>, Mykola Lysenko <mykolal@...com>, "Martin
KaFai Lau" <martin.lau@...ux.dev>, Song Liu <song@...nel.org>, Yonghong Song
<yonghong.song@...ux.dev>, KP Singh <kpsingh@...nel.org>, Hao Luo
<haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>, Shuah Khan
<shuah@...nel.org>, Alexandre Torgue <alexandre.torgue@...s.st.com>, "Jose
Abreu" <joabreu@...opsys.com>, Maxime Coquelin <mcoquelin.stm32@...il.com>,
"Nguyen, Anthony L" <anthony.l.nguyen@...el.com>, "Kitszel, Przemyslaw"
<przemyslaw.kitszel@...el.com>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
"bpf@...r.kernel.org" <bpf@...r.kernel.org>,
"linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>,
"linux-stm32@...md-mailman.stormreply.com"
<linux-stm32@...md-mailman.stormreply.com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>, "intel-wired-lan@...ts.osuosl.org"
<intel-wired-lan@...ts.osuosl.org>, "xdp-hints@...-project.net"
<xdp-hints@...-project.net>
Subject: RE: [PATCH bpf-next v6 4/4] igc: Add launch time support to XDP ZC
On Monday, January 20, 2025 2:26 PM, Abdul Rahim, Faizal <faizal.abdul.rahim@...ux.intel.com> wrote:
>Hi Siang.
>
>On 16/1/2025 11:53 pm, Song Yoong Siang wrote:
>> Enable Launch Time Control (LTC) support to XDP zero copy via XDP Tx
>> metadata framework.
>>
>> This patch is tested with tools/testing/selftests/bpf/xdp_hw_metadata on
>> Intel I225-LM Ethernet controller. Below are the test steps and result.
>>
>> Test Steps:
>> 1. At DUT, start xdp_hw_metadata selftest application:
>> $ sudo ./xdp_hw_metadata enp2s0 -l 1000000000 -L 1
>>
>> 2. At Link Partner, send an UDP packet with VLAN priority 1 to port 9091 of
>> DUT.
>>
>> When launch time is set to 1s in the future, the delta between launch time
>> and transmit hardware timestamp is equal to 0.016us, as shown in result
>> below:
>> 0x562ff5dc8880: rx_desc[4]->addr=84110 addr=84110 comp_addr=84110 EoP
>> rx_hash: 0xE343384 with RSS type:0x1
>> HW RX-time: 1734578015467548904 (sec:1734578015.4675) delta to User RX-
>time sec:0.0002 (183.103 usec)
>> XDP RX-time: 1734578015467651698 (sec:1734578015.4677) delta to User RX-
>time sec:0.0001 (80.309 usec)
>> No rx_vlan_tci or rx_vlan_proto, err=-95
>> 0x562ff5dc8880: ping-pong with csum=561c (want c7dd) csum_start=34
>csum_offset=6
>> HW RX-time: 1734578015467548904 (sec:1734578015.4675) delta to HW
>Launch-time sec:1.0000 (1000000.000 usec)
>> 0x562ff5dc8880: complete tx idx=4 addr=4018
>> HW Launch-time: 1734578016467548904 (sec:1734578016.4675) delta to HW
>TX-complete-time sec:0.0000 (0.016 usec)
>> HW TX-complete-time: 1734578016467548920 (sec:1734578016.4675) delta
>to User TX-complete-time sec:0.0000 (32.546 usec)
>> XDP RX-time: 1734578015467651698 (sec:1734578015.4677) delta to User TX-
>complete-time sec:0.9999 (999929.768 usec)
>> HW RX-time: 1734578015467548904 (sec:1734578015.4675) delta to HW TX-
>complete-time sec:1.0000 (1000000.016 usec)
>> 0x562ff5dc8880: complete rx idx=132 addr=84110
>
>To be cautious, could we perform a stress test by sending a higher number
>of packets with launch time? For example, we could send 200 packets, each
>configured with a launch time, and verify that the driver continues to
>function correctly afterward.
>
Hi Faizal,
Thanks for your review comments.
Sure, I can send continuous packets with short interval and share
the result in commit msg.
>> Signed-off-by: Song Yoong Siang <yoong.siang.song@...el.com>
>> ---
>> drivers/net/ethernet/intel/igc/igc_main.c | 78 ++++++++++++++++-------
>> 1 file changed, 56 insertions(+), 22 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c
>b/drivers/net/ethernet/intel/igc/igc_main.c
>> index 27872bdea9bd..6857f5f5b4b2 100644
>> --- a/drivers/net/ethernet/intel/igc/igc_main.c
>> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
>> @@ -1566,6 +1566,26 @@ static bool igc_request_tx_tstamp(struct igc_adapter
>*adapter, struct sk_buff *s
>> return false;
>> }
>>
>> +static void igc_insert_empty_packet(struct igc_ring *tx_ring)
>> +{
>> + struct igc_tx_buffer *empty_info;
>> + struct sk_buff *empty;
>> + void *data;
>> +
>> + empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use];
>> + empty = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC);
>> + if (!empty)
>> + return;
>> +
>> + data = skb_put(empty, IGC_EMPTY_FRAME_SIZE);
>> + memset(data, 0, IGC_EMPTY_FRAME_SIZE);
>> +
>> + igc_tx_ctxtdesc(tx_ring, 0, false, 0, 0, 0);
>> +
>> + if (igc_init_tx_empty_descriptor(tx_ring, empty, empty_info) < 0)
>> + dev_kfree_skb_any(empty);
>> +}
>> +
>
>The function igc_insert_empty_packet() appears to wrap existing code to
>enhance reusability, with no new changes related to enabling launch-time
>XDP ZC functionality. If so, could we split this into a separate commit?
>This would make it clearer for the reader to distinguish between the
>refactoring changes and the new changes related to enabling launch-time XDP
>ZC support.
>
I am ok to split the patch into two. Will do it on next version submission.
>> static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb,
>> struct igc_ring *tx_ring)
>> {
>> @@ -1603,26 +1623,8 @@ static netdev_tx_t igc_xmit_frame_ring(struct
>sk_buff *skb,
>> skb->tstamp = ktime_set(0, 0);
>> launch_time = igc_tx_launchtime(tx_ring, txtime, &first_flag,
>&insert_empty);
>>
>> - if (insert_empty) {
>> - struct igc_tx_buffer *empty_info;
>> - struct sk_buff *empty;
>> - void *data;
>> -
>> - empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use];
>> - empty = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC);
>> - if (!empty)
>> - goto done;
>> -
>> - data = skb_put(empty, IGC_EMPTY_FRAME_SIZE);
>> - memset(data, 0, IGC_EMPTY_FRAME_SIZE);
>> -
>> - igc_tx_ctxtdesc(tx_ring, 0, false, 0, 0, 0);
>> -
>> - if (igc_init_tx_empty_descriptor(tx_ring,
>> - empty,
>> - empty_info) < 0)
>> - dev_kfree_skb_any(empty);
>> - }
>> + if (insert_empty)
>> + igc_insert_empty_packet(tx_ring);
>>
>> done:
>> /* record the location of the first descriptor for this packet */
>> @@ -2955,9 +2957,33 @@ static u64 igc_xsk_fill_timestamp(void *_priv)
>> return *(u64 *)_priv;
>> }
>>
>> +static void igc_xsk_request_launch_time(u64 launch_time, void *_priv)
>> +{
>> + struct igc_metadata_request *meta_req = _priv;
>> + struct igc_ring *tx_ring = meta_req->tx_ring;
>> + __le32 launch_time_offset;
>> + bool insert_empty = false;
>> + bool first_flag = false;
>> +
>> + if (!tx_ring->launchtime_enable)
>> + return;
>> +
>> + launch_time_offset = igc_tx_launchtime(tx_ring,
>> + ns_to_ktime(launch_time),
>> + &first_flag, &insert_empty);
>> + if (insert_empty) {
>> + igc_insert_empty_packet(tx_ring);
>> + meta_req->tx_buffer =
>> + &tx_ring->tx_buffer_info[tx_ring->next_to_use];
>> + }
>> +
>> + igc_tx_ctxtdesc(tx_ring, launch_time_offset, first_flag, 0, 0, 0);
>> +}
>> +
>> const struct xsk_tx_metadata_ops igc_xsk_tx_metadata_ops = {
>> .tmo_request_timestamp = igc_xsk_request_timestamp,
>> .tmo_fill_timestamp = igc_xsk_fill_timestamp,
>> + .tmo_request_launch_time = igc_xsk_request_launch_time,
>> };
>>
>> static void igc_xdp_xmit_zc(struct igc_ring *ring)
>> @@ -2980,7 +3006,7 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring)
>> ntu = ring->next_to_use;
>> budget = igc_desc_unused(ring);
>>
>> - while (xsk_tx_peek_desc(pool, &xdp_desc) && budget--) {
>> + while (xsk_tx_peek_desc(pool, &xdp_desc) && budget >= 4) {
>
>Could we add some explanation on what & why the value "4" is used ?
It is because packet with launch time needs 2 descriptors and same goes
for the empty packets. Thus, total need 4 descriptors. I will add detail
explanation.
Thanks & Regards
Siang
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